4 ms·

Agree. It's an interesting technical challenge to ask for planes that can fly these long routes at present speeds, but I think we're solving the wrong problem.

Agree. It's an interesting technical challenge to ask for planes that can fly these long routes at present speeds, but I think we're solving the wrong problem. The problem is speed, not fuel efficiency.

ars 9y ago
Can't really go faster because we're already about 80% of the speed of sound. Going any closer to the speed of sound than that dramatically increases drag. Going higher (for less drag) is a problem because it's hard to keep the engines running in the thin air, and on top of that, high speed also makes it hard to keep them running. Until we figure out a new engine design, 80% of the speed of sound is about the max. Military engines get around this by consuming incredible amounts of fuel - not practical for commercial flights.
- willyt 9y ago
  I can't find a source that doesn't involve doing a lot of maths but I think a significant proportion of the fuel used by Concorde was taxiing, takeoff and climb out. In supercruise Concorde used less fuel than an 80's era 747 albeit carrying ~1/3 passengers but also for ~1/3 of the time. You just need a way to get you to 60000ft efficiently!
  - will_hughes 9y ago
    Even if you could, you can only go supersonic across oceans.
    - chx 9y ago
      If you could go Mach 2-3 then going above the Isthmus of Panama makes sense. It is only 33% longer http://www.gcmap.com/mapui?P=LHR-pty-syd&MS=wls2 http://www.gcmap.com/mapui?P=LHR-pty-syd&MS=wls2 http://www.gcmap.com/mapui?P=LHR-SYD http://www.gcmap.com/mapui?P=LHR-SYD and almost all of it is over an ocean.
    - rwmj 9y ago
      Apparently they're researching how to reduce the sonic boom problem: https://www.nasa.gov/aero/centers_tackle_sonic_boom.html https://www.nasa.gov/aero/centers_tackle_sonic_boom.html https://www.nasa.gov/centers/armstrong/features/flights_study_atmospheric_effect_on_sonic_booms.html https://www.nasa.gov/centers/armstrong/features/flights_stud...
- ubernostrum 9y ago
  Concorde was fuel-efficient as supersonic aircraft go, but the physics forces weird designs on you and you end up with, well, Concorde. Its cabin was cramped and not particularly comfortable, it cost much more than a regular airliner, and being supersonic didn't save enough time to cover the additional cost and discomfort. That's why we're still at 0.8-ish mach numbers -- you can build those planes big and comfortable for the people who buy the expensive tickets.
  - ghaff 9y ago
    Supersonic business jets seem plausible and the consensus seems to be that it could be a viable market if they could go supersonic over land. But larger planes seem a real stretch. Really long-haul routes might be getting into the range where people would be willing to sacrifice some seating space/amenities for a much faster plane. But then you're into needing much greater range than the Concorde. And, while there are a few of these routes that are economically viable on today's aircraft, even EWR-SIN didn't ultimately work out for Singapore Airlines.

ars 9y ago

Can't really go faster because we're already about 80% of the speed of sound. Going any closer to the speed of sound than that dramatically increases drag. Going higher (for less drag) is a problem because it's hard to keep the engines running in the thin air, and on top of that, high speed also makes it hard to keep them running. Until we figure out a new engine design, 80% of the speed of sound is about the max. Military engines get around this by consuming incredible amounts of fuel - not practical for commercial flights.

willyt 9y ago
I can't find a source that doesn't involve doing a lot of maths but I think a significant proportion of the fuel used by Concorde was taxiing, takeoff and climb out. In supercruise Concorde used less fuel than an 80's era 747 albeit carrying ~1/3 passengers but also for ~1/3 of the time. You just need a way to get you to 60000ft efficiently!
- will_hughes 9y ago
  Even if you could, you can only go supersonic across oceans.
  - chx 9y ago
    If you could go Mach 2-3 then going above the Isthmus of Panama makes sense. It is only 33% longer http://www.gcmap.com/mapui?P=LHR-pty-syd&MS=wls2 http://www.gcmap.com/mapui?P=LHR-pty-syd&MS=wls2 http://www.gcmap.com/mapui?P=LHR-SYD http://www.gcmap.com/mapui?P=LHR-SYD and almost all of it is over an ocean.
  - rwmj 9y ago
    Apparently they're researching how to reduce the sonic boom problem: https://www.nasa.gov/aero/centers_tackle_sonic_boom.html https://www.nasa.gov/aero/centers_tackle_sonic_boom.html https://www.nasa.gov/centers/armstrong/features/flights_study_atmospheric_effect_on_sonic_booms.html https://www.nasa.gov/centers/armstrong/features/flights_stud...
ubernostrum 9y ago
Concorde was fuel-efficient as supersonic aircraft go, but the physics forces weird designs on you and you end up with, well, Concorde. Its cabin was cramped and not particularly comfortable, it cost much more than a regular airliner, and being supersonic didn't save enough time to cover the additional cost and discomfort. That's why we're still at 0.8-ish mach numbers -- you can build those planes big and comfortable for the people who buy the expensive tickets.
- ghaff 9y ago
  Supersonic business jets seem plausible and the consensus seems to be that it could be a viable market if they could go supersonic over land. But larger planes seem a real stretch. Really long-haul routes might be getting into the range where people would be willing to sacrifice some seating space/amenities for a much faster plane. But then you're into needing much greater range than the Concorde. And, while there are a few of these routes that are economically viable on today's aircraft, even EWR-SIN didn't ultimately work out for Singapore Airlines.